256 NEW YORK STATE' MUSEUM 



connected with the genital vestibule, the origin of the vagina be- 

 ing immediately posterior to that of the penis. The vaginal body 

 is cylindrically oval in form^ having a length of from two and one 

 half to three times the diameter. The walls of the vagina are 

 strong, thick, and consist of muscular fibers. Internally there 

 are a number of strong regular, longitudinal muscular elevations, 

 covered by a double membrane. Near the base these folds are pli- 

 cated, but become smooth above. At its extremity the vagina nar- 

 rows into a thin-walled tube or duct, which is of varying length, 

 sometimes short, at other times as long as the vagina. This 

 duct becomes dilated above, forming the receptaculum seminis. 

 The latter organ is elongate oval in form, having very thin walls, 

 and with minute longitudinal folds along the interior (pi. 8, fig. 

 10, 11, 14). These folds sometimes give a striated appearance to 

 the exterior. The organ is in contact with and closely adhering 

 to the oviduct. 



During coition the penis is inserted in the vagina, and is there 

 closely held by the muscular walls and longitudinal folds, the 

 spermatozoa finding their way into the receptaculum seminis, 

 afterward passing down through the vagina, and fertilizing the 

 egg as it leaves the oviduct. 



In addition to being a receptacle for the spermatozoa, the 

 receptaculum seminis, according to Dr Leidy^ ^' secretes a mucoid 

 matter^ which probably facilitates the passage of the ova through 

 the cloaca. The mucus matter in the bladder is frequently found 

 to contain an immense number of an infusorial parasite, which I 

 have described under the name C r y p t o i c u s. " ^ 



Dr Leidy's description is given at the end of the article on the 

 generative organs. 



Ovotestis. The ovotestis, in common with the superior organ 

 of the digestive gland, occupies the apical volutions of the ani- 

 mal (pi. 7, fig. 1, 12). It is lighter in appearance than the digestive 

 gland, and is composed of a number of bundles or fasciculi of 

 short ceca. Each fasciculus is composed of numerous ceca, is 



1 Terrestrial moll, and shells of the United States, p. 234. 



2 Jour. acad. nat. sci, new series, v. i. 



